Page 399 - Medicine and Surgery

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Chapter 9: Facial dermatoses 395

Investigations Increasedandrogensaroundpubertyandanincreased
It is a clinical diagnosis; however, biopsy of affected skin sensitivity to androgens causes hyperplasia of the se-
shows a subepidermal blister with neutrophil infiltra- baceousglandsandincreasesebumproduction.Accu-
tion. Immunofluorescence staining of skin biopsy taken mulation of the sebum in a follicle obstructed by hy-
from an unaffected area shows granular IgA deposits perkeratosis creates a closed comedo or white-headed
along the basement membrane. Serological testing and spot. Reopening of the follicle due to distension causes
small bowel biopsy may be required to identify gluten the formation of an open comedo, which appears as a
sensitivity (see page 165). blackhead.
Propionibacterium acnes,an anaerobic commensal of

Management the skin, is able to grow in the anaerobic environment
Even without clinical coeliac disease patients often re- producedbythecombinationofincreasedsebumpro-
spond to a gluten-free diet. The rash responds dramat- duction and blockage of the follicular canals.
ically to dapsone (this has been used as a diagnostic Rupture of a follicle into the dermis and/or the hy-
test). The concomitant use of cimetidine (which inhibits drolysis of lipids in the sebum by P. acnes results in an
cytochrome p450 enzymes) helps to reduce side effects inflammatory reaction that may cause cysts, pustules,
caused by the metabolic products of dapsone. papules, and scarring.
Exacerbating factors include excess androgen produc-

tion, oily creams and cosmetics, humidity and heavy
Prognosis
Condition often shows relapses and remissions. sweating. Mechanical trauma such as excessive scrub-
bing increases inflammation and scarring. Diet does
not affect sebum production or acne. Excess steroids,
Facial dermatoses either endogenous or exogenous, can induce a pustu-
lar form of acne mainly affecting the back and shoul-
ders. Infantile acne is a self-limiting condition seen in
Acne vulgaris babies due to the effect of maternal androgens.

Definition
Acne is a chronic inflammatory disease of the piloseba- Clinical features
ceous units, which may result in comedones (black- or Lesions occur at sites where there are many sebaceous
white-headed spots), papules, pustules, cysts and scars. glands such as face, shoulders, back and upper chest.
Scars may follow healing particularly when cysts have
Prevalence formed, leaving skin depressions, and may result in
Acne will affect approximately 85% of individuals at keloid formation.
some time.
Management
Age Local treatments include topical retinoids, which nor-
Generally confined to adolescence but may persist. malise keratinisation and prevent follicular blockage,
benzoyl peroxide, a keratolytic agent, and topical an-
Sex tibiotics, such as tetracycline. These may be used in
M = F(females affected earlier). combination in more severe acne.
Systemic treatments are used for refractory acne or if

Aetiology/pathophysiology scarring occurs:
The process of acne begins in the keratinocytes within Low-dose oral antibiotics such as erythromycin, tetra-

thefolliclesofthepilosebaceousglands.Increasedpro- cycline or trimethoprim may be used but need to be
liferation and reduced loss of keratinocytes increases continued for up to 6 months.
their number and blocks the follicles with a hyperker- Cyproterone acetate and ethinyl oestradiol, a com-
atotic plug (microcomedo). bined oral contraceptive, also has an antiandrogen